Combined filter and press



Dc. 31, 1940. c. w. GoRDoN 2,226,926

COMBINED FILTER AND PRESS Filed Oct. 25, 1937 E l! Z0; j; i 5;; 14 fg 13 40 INVENTOR ATTORNEY Patented Dec. 31, 1940 UNITED STATES PATENT OFFICE COMBINED FILTER AND PRESS Charles W. Gordon, Glen Ellyn, Ill., assignor to Combustion Engineering Company, Inc., New

York, N. Y.

4 Claims.

The present improvement relates to the art of screening solid materials, carried in suspension in a liquid, out of such liquid and forcing further liquid out of the screened solids, or tails by means of a press, and is more particularly concerned with cases where the solids carried in suspension are of varying sizes including very iine particles. A typical instance of this sort is that of distillery slop.

When such assorted sizes of materials are to be screened out of a liquid, it is found at once that to carry on the process at a reasonable speed and in such a Way that the filtered material comes from the filter without excessive moisture, it is practically necessary to filter through two or more screens of different number of mesh. A practical installation may for example use two screens, the slop being fed in the iirst place on a 30 mesh per inch screen, the eilluent from this filter being run on to a filter of 200 mesh per inch. If a single 200 mesh filter were used and all of the slop fed directly to it, the action would be slowed up very much and the material screened out would come from the lter vdfy much wetter than when the two mesh lter referred to is used. The reason for this is that in the former case the fine material is intimately mingled with the coarser material, closing up the nterstices between the coarser particles so that the drainage through the mass is nearly as slow as if the Whole mass were made up of line particles. If however the coarser particles are filtered out rst, then the drainage through this portion of the mass is very much more rapid and thorough, and the portion of the mass in which the ltration is slow and not very thorough is reduced to a minimum. The total moisture retained by the two masses is as a consequence much smaller than with a single fine mesh filter. In the case of distillery slops, the relative proportions of the two masses will be ,for example, as follows: The 30 mesh screen may retain approximately lbs. of wet ltrate per bushel of slop processed and the 200 mesh screen may retain approximately 2 lbs., the ratio thus being 5 to l.

The moisture content of the filtrate is in any case such that a great portion `of it can be removed by a suitable press. If, as is regular practice, the filtrate from the 30 mesh iilter is mingled with that from the 200 mesh and the resulting mixture put through a press, it is found that the eiiluent carries an entirely too large proportion of the fines with it.

The object of the present invention is to remedy this condition by providing a novel apparatus for treating the wet material coming from the filter. With this novel apparatus it will be found that in addition to reducing the amount of iine material carried off by the eilluent, a further beneiit results which is that a much drier product from the press can be obtained than could be obtained from presses as operated heretofore.

The present application is a division of application Serial No. 113,023, led on November 27,

1936 and now matured into Patent No. 2,149,017,

dated February 28, 1939.

The invention is illustrated in, and will be discussed in connection with, the drawings on the single sheet iiled herewith in which Fig. 1 shows a lateral elevation, partly in section, of an installation utilizing the improved apparatus. Fig. 2 is a sectional view on line 2-2 of Fig. 1 and Fig. 3 is a sectional View on line 3 3 of Fig. 1.

The material to be treated is fed to the filter through the spout l. It falls on the 30 mesh screen 2 where a substantial part of the solid particles are retained. As mentioned above, this may be about 80 to 90% of the total. The water flowing through the screen and carrying the finer particles with it falls upon the 200 mesh screen 3. This retains all of the suspended solids left which it is practically advisable to lter out. The eiiluent falls to the bottom of the screen housing and flows down to the outlet trough 4.

The type of screen illustrated inthe drawing is a well known commercial type which gives a horizontal rotary motion to one end of the screen, the power being furnished by a motor 6. The mechanism for giving this motion is indicated at 8. The opposite end I Il of the screen is guided to give this end a reciprocating movement. The screen is inclined and the whole arrangement is such that the material caught on screens 2 and 3 is gradually fed down toward the lower or left end and is discharged at Il and I2 respectively. 'I'he particular type of screen or its action are not per se a part of the present invention and any device that separates the grain as indicated will answer the purpose.

The press itself which I utilize is likewise of a commercially available type. 1t may briefly be described as follows: Within the casing 55 two discs |4-I4 are mounted to rotate about their axes IG-lS being driven by means of the circumferentially arranged gear teeth l8--I8 engaging the spur gears 20. These spur gears are each mounted on an axle 22, and on each axle 22 there is mounted a gear wheel 24, which are driven by the spur gear 20. These spur gears 26-28 are mounted on shaft 28, which is driven by any suitable means.

It will be noted that the axes IB-IG are inclined away from the horizontal in opposite directions and that the faces 30 of the discs I4 are bluntly conical. Each surface 30 is perforated as indicated at 32 and has mounted on it a perforated plate 34. This in turn has mounted on it a screen cloth 38. The openings in the disc 30 and in the plate 34 are fairly large and readily allow anything to flow away through 'them which is passed by the screen cloth 36. 'I'he screen cloth has rather fine perforations, these being in practice about a millimeter in diameter.

It will be noted that the two frusto-conical surfaces are very close to each other and that elements of the opposite portions of the conical surfaces are parallel to each other in the region vertically the center and diverge at the region directly above the center. At intermediate points they approach each other more and more closely as the lowest point is approached.

This press is, as stated, a commercially available one and operates briefly as follows: Matel rial to be pressed is fed in from above and at one side of the axes |6-I6. As the discs are rotated, this material is carried downward toward the lowest point, the space available for it be-coming more and more restricted, with the result that its moisture is pressed out through the cloth. .This moisture then leaves through the perforations in the plates and flows downward and is discharged at 4|).

Under prior practice the material from the 30 mesh and that from the 200 mesh screens were fed into the press together and mingled, with the result, pointed out above, that a great proportion of the fines was pressed out throughl the screen cloth.

The perforatlons through the screen cloth are of such size that the screen cloth retains substantially all of the coarser material but rather readily passes material of the size caught by the 200 mesh lter. The perforations cannot be made smaller without seriously interfering with the flow of the liquid through the cloth..

By my improved device and in accordance with my improved process I feed the fine material into the press in such a manner that it ls surrounded by coarser material on all sides. From Figs. l and 2, for example, it will be clear that the fine material from I2 falls into the funnel-shaped entrance 42 which delivers it through the channel 44 to the press, surrounded on three sides at 46, 48 and 50 by coarser material from the 30 mesh lter 2 coming in through the spout Il. The fourth side need not be closed in with the coarser material in this particular press, as the material here does not lie against screen cloth, but against the solid hub 3l. As a result the fine material nowhere comes in contact with the screen cloth 36 through which it might pass. Particles of this ilne mass may be carried a little distance into the coarser material but will be caught by such coarser material and held and kelt from reaching and penetrating this screen clo h.

Inasmuch as the liner material is prevented from reaching the screen cloth and from being carried along by the liquid which has been pressed out and forced through the screen cloth, it is now found that a much higher pressure can be applied in the press. Another factor enters here to make the application of higher pressures possible when the present process is used. It is possible to apply pressure to masses of such granular material generally only because there is frlctional resistance to movement of the particles over each other. The more of this frictional resistance exists, the higher the pressures that can be applied. Now the very fine particles where they are present act in the nature of a lubricant and by segregating them and putting them in the central area, this lubrication action is removed. With the present process the pressure may be raised from 50 to 60 pounds per square inch to 125. The cake coming from the press is therefore very much drier and this is a great advantage when the material is to be dried further, as is usually the case, such further drying being performed by evaporation and therefore being relatively expensive.A

The nature of the invention will be clear from the above and it will be likewise clear that the application of the inventive idea is not limited to any particular form or type of press. In fact, the invention can obviously be used equally well in connection with a centrifuge. All that is re- `quired to take advantage of the invention is that the coarser material from the 30 mesh screen be interposed between the mass of liner particles and every surface by which the moisture forced out leaves the press.

While I have described the invention in the above with particular reference to distillery slops and have mentioned particular sizes of particles, filter screens and press screens, it will be understood that this is not intended in any way as a limitation but merely by way of illustration. It will likewise be obvious that many variations can be made in the particular apparatus described Without departing from the inventive thought.

What I claim is:

1. In apparatus of ther class described for pressing moisture out of wet material made up` of grains of various sizes and separated into at least two portions according to size of grain, the combination of a press comprising a screen against which the material is pressed and through which the moisture is forced, and means to feed the material into the press with a layer of coarser grain material separating finer grain material from the screen.

2. In apparatus of the class described for pressing moisture out of wet material made up of grains of various sizes and separated into two portions according to size of grain, the combination of a press comprising a cloth screen, means to feed a layer of the coarser grain portion into the press covering the screen, means to feed the ner grain portion into the press in contact with the surface of the coarser grain layer away from the screen, and means to press the two layers toward the screen thereby forcing the moisture through the screen, whereby the fine grain particles are prevented by the layer of coarse grain material from passing through the screen.

3. In apparatus of the class described for pressing moisture out of wet granular material made up of two portions one including substantially all the grains below a predetermined size and the other including all the remaining grains, the combination of a press comprising a cloth screen through which at least some of the grains of the rst portion but substantially none of the grains of the second portion can pass, means to cover the screen with a layer of the second portion, means to cover said first-named layer with a layer ofthe rst portion, means to press the two layers toward the screen thereby forcing the moisture through the screen, and means to remove the pressed material from the press.

4. In a press of the class described comprising two obtusely conical perforated plates covered with cloth screens, the two plates being rotatably. mounted so that their faces are closely spaced and substantially parallel from their ap- 10 proximately horizontal axes downward and diverge ln all other directions. the divergence being greatest from the axes upward, means to feed into the press wet granular material made up of two portions one including substantially all the grains below a predetermined size and the other including all the other grains, the feeding means being such as to feed the two portions so that the second portion forms a layer everywhere between the cloth screen and the rst portion.

CHARLES W. GORDON. 

